Networks of Neurodevelopmental Traits, Socioenvironmental Factors, Emotional Dysregulation in Childhood, and Depressive Symptoms Across Development in Two U.K. Cohorts

Objective Previous population-based studies have identified associations between childhood neurodevelopmental traits and later depression. However, neurodevelopmental traits are highly correlated, which could confound associations when traits are examined in isolation. The authors sought to identify the unique associations between multiple neurodevelopmental traits in childhood and depressive symptoms over development while also considering co-occurring difficulties in multivariate analyses. Methods Data from two UK population-based cohorts, the Twins Early Development Study (N = 4,407 independent twins) and the Avon Longitudinal Study of Parents And Children (N = 10,351), were independently analyzed. Bayesian Gaussian graphical models were estimated to investigate pairwise conditional associations between neurodevelopmental traits (autistic, ADHD symptoms; general cognitive, learning, communication abilities), social-environmental stressors (academic performance, peer relations), emotional dysregulation in childhood (7-11 years) and depressive symptoms across development (12, 16, and 21 years). Results In both cohorts, there were several unadjusted associations between neurodevelopmental traits and depressive symptoms over development. However, these pairs of variables were mostly found conditionally independent, and none were conditionally associated, after accounting for social-environmental stressors, emotional dysregulation. In turn, social-environmental stressors and emotional dysregulation were conditionally associated with both neurodevelopmental traits and depressive symptoms. Based on replicated data across cohorts, neurodevelopmental traits in childhood could only be indirectly associated with depressive symptoms over development. Conclusions This study indicates that associations between childhood neurodevelopmental traits and depressive symptoms over development could be explained by social-environmental stressors and emotional dysregulation. The present findings could inform future research aimed at the prevention of depression in youth with neurodevelopmental disorders.

the associations from gaussian graphical models (GGMs) are conditional on the variables that are included in the model (3), we opted to only include variables which were available from the two cohorts.
• Main analysis plan: Our original analysis plan was based on the traditional frequentist approach for psychological network analyses and was heavily influenced by previous studies in the field, e.g., Fried et al., who evaluated in a series of stepwise models whether associations between depression symptoms and inflammation markers survived incorporation of covariates in their models (4).Upon reflection, however, in the traditional frequentist approach there are no guarantees that unselected edges are statistically indistinguishable from zero or that evidence for their absence is strong (3).Therefore, we opted to adopt the Bayesian approach to estimate our models instead because it allows for quantification of the evidence against edge inclusion and hypothesis testing (5,6).We also did not create stepwise models because adding variables to a GGM increases the sampling variability of a partial correlation, which in turn reduces the chances that the association is detected (7).
• Sensitivity analyses plan: We originally proposed to conduct a separate analysis with data from the other random twin from TEDS to replicate findings from the main analysis, also from TEDS.However, because we acquired independent data from a different cohort study (ALSPAC) we opted not to conduct those analyses, which would be based on dependent data and therefore would provide weaker evidence of replicability.We also originally proposed to estimate models with only data from individuals with 'neurodevelopmental difficulties' as described by Eyre et al. (8).However, individuals with neurodevelopmental difficulties would be determined based on cut-off values and there is evidence that this procedure is associated with worse recovery of the network structure and may introduce bias in the analyses (9).Lastly, we planned to conduct a sensitivity analysis including parentreported depressive symptoms at ages 12 and 16 years.However, because we only had self-reported scores at age 21 years, we opted not to conduct the sensitivity analysis mixing informants, which could be inconclusive.'8$,:9',(:+.*3n$X"J3SU$m)1::4.,)'*,1.$,:9',(:

Attention-deficit/hyperactivity disorder (ADHD) symptoms
The Conners parent rating scale-revised (CPRS-R) (19) contains 18 items which query about symptoms of DSM-IV defined ADHD (DSM-IV symptom subscale) over the past month.The CPRS-R has sound psychometric properties in school-aged children (19).Items were rated 0 ('not true at all'), 1 ('just a little true'), including ADHD (20).In ALSPAC, the DAWBA was used as a parent-reported questionnaire only."Section K: Attention and activity" queries about ADHD symptoms over the past 6 months with questions closely related to DSM-IV operational criteria.Items were rated 0 ('No'), 1 ('A little more than others') and 2 ('A lot more than others').Continuous scores for each subscale (hyperactivity/impulsivity and inattention) were computed by summing the 9 items of each subscale separately.For both subscales, at least 5 of the items were required to be non-missing to compute prorated scores.Higher scores indicate more ADHD symptoms.

General cognitive ability
The general cognitive ability (g) score was created as the average of standardized scores on two verbal

Communication ability
The Children's Communication Checklist (CCC) ( 23) is a parent-rated questionnaire aimed at measuring communication impairments in children.The CCC is composed of 70 items divided in nine subscales (subscales A to I), five of which (subscales C to G) are summed to compose a measure of pragmatic aspects of communication.In the original description of the instrument, items are negative and rated 'does not apply' (0), 'applies somewhat' (-1), and 'definitely applies' (-2).Some of the items are positive, please refer to the article by Bishop (23) for a comprehensive description.Higher scores indicate better communication ability (23).The CCC has sound psychometric properties in school-aged children.(23).
To avoid overburdening families, a shortened version of the scale with 53 items (subscales A to G) was used in ALSPAC.Items were positively scored on a 3-point Likert scale and some items were reverse scored.Please refer to the ALSPAC dictionary for additional details about scoring rules of each item.The sum of subscales A and B correspond to the speech & syntax score, whereas the sum of subscales C to G correspond to the pragmatic score -as defined above.A minimum of 6 (subscale A), 4 (subscale D to G), 3 (subscale C) and 2 (subscale B) items were required to be non-missing to compute prorated scores.
In TEDS, an even shorter version with only 12 items (5 items from subscale A; 3 items from subscale B; and 4 items from subscale D) of the original 70-item instrument was applied.Items were rated considering the same rules adopted for ALSPAC.We computed subscale scores for TEDS by summing the 8 items from subscales A and B (speech & syntax) and the 4 items from subscale D (pragmatic) separately.We required at least 4 and 2 items to be non-missing to compute prorated speech & syntax and pragmatic scores, respectively.
sound psychometric properties (28,30).In both TEDS and ALSPAC, we required at least 3 items to be nonmissing to compute prorated scores.

Depressive symptoms
The short mood and feelings questionnaire (sMFQ) is a questionnaire derived from the 33-item MFQ (31) which evaluates core depressive symptoms over the past two weeks.The sMFQ has sound psychometric properties in both children/adolescents (32) and young adults (33).The sMFQ has 13 items which are rated as 'not true' (0), 'sometimes true' (1) and 'true' (2).Total scores were computed by summing the 13 items, but in TEDS for adults (21 years) total scores were generated by summing the 8 items which were administered.In TEDS, prorated scores were computed if at least 7 items were not missing for children (12 years) and adolescents (16 years); for adults (21 years), if at least 4 items were not missing.In ALSPAC, sMFQ scores were collected through in-person assessments and complete data were available.

Supplement G. Zero-order correlations
Table S3.Pearson Values represent Pearson's r with 95% confidence intervals.Bold indicates associations for which zero-order correlations were statistically significant at a Bonferroni-adjusted p < 2.38*10 -3 in both cohorts and for which there was sufficient evidence of conditional independence based on GGM analyses.Grey shading indicates associations for which zero-order correlations were statistically significant at a Bonferroni-adjusted p < 2.38*10 -3 in both cohorts and for which evidence from GGMs was inconclusive (i.e., incongruent across cohorts or ambiguous in at least one cohort).Regression coefficients considering domains in columns as the dependent variables (Y) and domains in rows as the independent variables (X).The index of mediation is calculated by multiplying the regression coefficients as previously described (34).Grey shading indicates associations for which findings across TEDS and ALSPAC were either ambiguous in at least one cohort or discordant across cohorts.

Supplement I. Standardized regression coefficients
Abbreviations  Neurodevelopmental traits, social-environmental stressors, and co-occurring emotional dysregulation.
In TEDS, academic competence and adult depressive symptoms were classified as ambiguous.In ALSPAC, educational achievement and childhood depressive symptoms were classified as ambiguous.Variables are represented as nodes (circles) and are colored according to their community as identified by the spinglass algorithm.Edges between two nodes represent partial correlations between two variables.The width of edges is proportional to the strength of the partial correlation.Positive and negative partial correlations were colored in blue and red, respectively.

Summary of changes from the main analyses
Neurodevelopmental traits.
In TEDS, the association between autistic symptoms and general cognitive ability was classified as ambiguous.Intriguingly, some of the associations were discordant in the sensitivity analysis.Specifically, three pairs of variables were found conditionally independent: inattention symptoms and general cognitive ability; learning ability and pragmatic aspects of communication ability; autistic symptoms and pragmatic aspects of communication ability.Additionally, a negative correlation between learning ability and speech & syntax aspects of communication ability was found in the sensitivity analysis.
In TEDS, academic competence and adult depressive symptoms were classified as ambiguous.In ALSPAC, emotional dysregulation and childhood depressive symptoms were classified as ambiguous.Variables are represented as nodes (circles) and are colored according to their community as identified by the spinglass algorithm.Edges between two nodes represent partial correlations between two variables.The width of edges is proportional to the strength of the partial correlation.Positive and negative partial correlations were colored in blue and red, respectively.

Summary of changes from the main analyses
Neurodevelopmental traits.
In TEDS, the association between autistic symptoms and general cognitive ability was classified as ambiguous.Additionally, the associations between communication abilities and learning ability were also classified as ambiguous.In ALSPAC, the following pairs of variables were classified as ambiguous: autistic symptoms and learning ability; speech & syntax aspects of communication ability and general cognitive ability.
In TEDS, the following pairs of variables were classified as ambiguous: inattention symptoms and adolescent depressive symptoms; speech & syntax communication ability and peer problems; academic competence and adult depressive symptoms.In ALSPAC, autistic symptoms, emotional dysregulation, academic performance and childhood depressive symptoms were classified as ambiguous.Variables are represented as nodes (circles) and are colored according to their community as identified by the spinglass algorithm.Edges between two nodes represent partial correlations between two variables.The width of edges is proportional to the strength of the partial correlation.Positive and negative partial correlations were colored in blue and red, respectively.

2 (
'pretty much true')  or 3 ('very much true').Continuous scores for each subscale (hyperactivity/impulsivity, inattention) were computed by summing the 9 items of each subscale separately.For both subscales, at least 5 of the items were required to be non-missing to compute prorated scores.Higher scores indicate more ADHD symptoms.The Development and Well-Being Assessment (DAWBA) (20) is a structured interview (yes/no) for children aged 4-16 years old administered by lay interviewers which integrates information from multiple informants (e.g., caretakers, teachers and self-reports for children aged 11 years or older).In Britain, DAWBA has demonstrated good reliability and discriminative ability for the diagnosis of multiple psychiatric conditions and non-verbal tests.The two verbal tests were adapted from the Wechsler Intelligence Scale for Children-III (WISC-III)(21).One of the verbal tests involved general knowledge questions (e.g.,'on what continent is Brazil?') to evaluate the individual's ability to acquire, retain and retrieve information.The other verbal test involved vocabulary questions (e.g., 'what does rivalry mean') to measure knowledge and verbal concept formation.The two non-verbal tests were adapted from the Cognitive Abilities Test 3 (CAT3)(22).One of the tests asked children to identify the shape out of five which would continue a series to measure inductive reasoning and visualization.The other test asked children to identify the one shape out of five that would be related to another shape in a similar way as a given example (e.g., a rectangle and a square relate to each other like an oval and what other shape?) to measure inductive and deductive reasoning.Higher scores indicate higher general cognitive ability.The full-scale intelligence quotient (IQ) score was derived from ten shortened subtests adapted from the WISC-III, five each for verbal (vocabulary, similarities, arithmetic, information, comprehension) and performance/non-verbal (object assembly, coding, block design, picture arrangement, picture completion) subtests.Children were required to have at least 8 subtests (with more than 4 for each verbal/performance domain) to compute prorated scores.Higher scores indicate higher general cognitive ability.
Abbreviations: A = Autistic symptoms; ADO-DEP = Adolescent depressive symptoms; ADU-DEP = Adult depressive symptoms; C-DEP = Childhood depressive symptoms; C-P = Pragmatic sub-domain of communication ability; C-SS = Speech & syntax sub-domain of communication ability; GEN COG = General cognitive ability; HY = Hyperactivity/impulsivity sub-domain of ADHD symptoms; IN = Inattention sub-domain of ADHD symptoms; LD-R = Learning ability.Supplement H. Predictability values for each variable.

Figure S2 . 2 . 4 )
Figure S2.Network plots for neurodevelopmental traits, social-environmental stressors, and co-occurring emotional dysregulation in childhood (7-11 years old) and depressive symptoms over development in childhood (12 years), adolescence (16 years) and adulthood (21 years) in the Twins Early Development Study (top) and the Avon Longitudinal Study of Parents And Children (bottom) after decreasing the prior scale.Variables are represented as nodes (circles) and are colored according to their community as identified by the spinglass algorithm.Edges between two nodes represent partial correlations between two variables.The width of edges is proportional to the strength of the partial correlation.Positive and negative partial correlations were colored in blue and red, respectively.

Figure S3 .
Figure S3.Network plots for neurodevelopmental traits in childhood (7-10 years old) in the Twins Early Development Study (top) and the Avon Longitudinal Study of Parents And Children (bottom) after increasing the prior scale.Variables are represented as nodes (circles) and are colored according to their domain.Edges between two nodes represent partial correlations between two variables.The width of edges is proportional to the strength of the partial correlation.Positive and negative partial correlations were colored in blue and red, respectively.

Figure S4 .
Figure S4.Network plots for neurodevelopmental traits, social-environmental stressors, and co-occurring emotional dysregulation in childhood (7-11 years old) and depressive symptoms over development in childhood (12 years), adolescence (16 years) and adulthood (21 years) in the Twins Early Development Study (top) and the Avon Longitudinal Study of Parents And Children (bottom) after increasing the prior scale.Variables are represented as nodes (circles) and are colored according to their community as identified by the spinglass algorithm.Edges between two nodes represent partial correlations between two variables.The width of edges is proportional to the strength of the partial correlation.Positive and negative partial correlations were colored in blue and red, respectively.

Figure S5 .
Figure S5.Network plots for neurodevelopmental traits in childhood (7-10 years old) in the Twins Early Development Study (top) and the Avon Longitudinal Study of Parents & Children (bottom) after excluding individuals with > 30% missing neurodevelopmental data.Variables are represented as nodes (circles) and are colored according to their domain.Edges between two nodes represent partial correlations between two variables.The width of edges is proportional to the strength of the partial correlation.Positive and negative partial correlations were colored in blue and red, respectively.

Figure S6 .
Figure S6.Network plots for neurodevelopmental traits, social-environmental stressors, and co-occurring emotional dysregulation in childhood (7-11 years old) and depressive symptoms over development in childhood (12 years), adolescence (16 years) and adulthood (21 years) in the Twins Early Development Study (top) and the Avon Longitudinal Study of Parents & Children (bottom) after excluding individuals with > 30% missing neurodevelopmental data.Variables are represented as nodes (circles) and are colored according to their community as identified by the spinglass algorithm.Edges between two nodes represent partial correlations between two variables.The width of edges is proportional to the strength of the partial correlation.Positive and negative partial correlations were colored in blue and red, respectively.

Figure S7 .
Figure S7.Network plots for neurodevelopmental traits in childhood (7-10 years old) in the Twins Early Development Study (top) and the Avon Longitudinal Study of Parents & Children (bottom) after adjusting for age at data collection and sex.Variables are represented as nodes (circles) and are colored according to their domain.Edges between two nodes represent partial correlations between two variables.The width of edges is proportional to the strength of the partial correlation.Positive and negative partial correlations were colored in blue and red, respectively.

Figure S8 .
Figure S8.Network plots for neurodevelopmental traits, social-environmental stressors, and co-occurring emotional dysregulation in childhood (7-11 years old) and depressive symptoms over development in childhood (12 years), adolescence (16 years) and adulthood (21 years) in the Twins Early Development Study (top) and the Avon Longitudinal Study of Parents & Children (bottom) after adjusting for age at data collection and sex.Variables are represented as nodes (circles) and are colored according to their community as identified by the spinglass algorithm.Edges between two nodes represent partial correlations between two variables.The width of edges is proportional to the strength of the partial correlation.Positive and negative partial correlations were colored in blue and red, respectively.

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Most variables are questionnaire-based and were collected through web-based forms or pencil-andpaper booklets, while others were collected as web tests or in-person assessments.Measures were completed by parents, teachers, or the individuals themselves.Most measures are validated, but to reduce burden on participants, only a subset of items of the instruments measuring communication ability in both cohorts and depression in TEDS at age 21 years were administered.Additionally, measures of cognitive and learning abilities involved subsets and/or adaptations of validated tests.

Table S2 .
Bayes Factor (BF 10 ) in support of ℋ 1 :  ≠ 0 against ℋ 0 :  = 0 and vice-versa (BF 01 ) for each pair of variables in the Twins Early Development Study (TEDS) and the Avon Longitudinal Study of Parents And Children (ALSPAC) 's correlation for each pair of variables in the Twins Early Development Study (TEDS) and the Avon Longitudinal Study of Parents And Children (ALSPAC)

Table S4 .
Bayesian R 2 for each pair of variables in the Twins Early Development Study (TEDS) and the Avon Longitudinal Study of Parents And Children (ALSPAC)

Table S5 .
Standardized regression coefficients for each pair of variables in the Twins Early Development Study (TEDS) and the Avon Longitudinal Study of Parents And Children (ALSPAC)